Meridian of a sphere
= Meridian of a sphere
= Meridian
{synonym}
A <great circle> passing through a chosen pair of antipodal poles, or the pole-to-pole half of that circle at fixed longitude. In <spherical coordinates>, a fixed azimuth selects such a half-circle. Meridians are special cases of a <meridian of a surface of revolution> and are <geodesics> of the <sphere>.